Method and apparatus for performing video communication

ABSTRACT

A method for performing video communication is provided. The method includes: creating and saving a bio key using a user&#39;s biological information before first and second terminals perform the video communication; establishing a session, wherein the first terminal requests voice communication with the second terminal; exchanging bio keys saved in the respective terminals and saving the same; starting a Secure Real-Time Transport Protocol (SRTP) session, wherein the first and second terminals create a session sharing key using the exchanged bio keys; creating a restored bio key by obtaining the biological information from data received by first and second terminals and performing a user certification by comparing the bio key with the restored bio key.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2008-0120142, filed on Nov. 28, 2008 in the Korean IntellectualProperty Office, the disclosure of which is hereby incorporated byreference in its entirety.

BACKGROUND

1. Field

Methods and apparatuses consistent with the exemplary embodiments relateto a method and an apparatus for performing video communication, andmore particularly to performing video communication which encrypts dataused in the video communication through a digital key.

2. Description of the Related Art

In general, video communication using Internet protocol networks orwireless networks has been in widespread use. Voice communication istypically concerned with an exchange of voice information between users.However, when a user utilizes video communication, the user can exchangea variety of information using a video or an image. Particularly, in theprocess of exchanging business information, for example, a blueprint, avideo of a portion of a document, a drawing of a product design or thelike using video communication, such information may be exposed to anill-spirited hacker, which can lead to serious damages. Accordingly,security measures for video communication should be taken to protect theinformation being exchanged.

To provide security for wired or wireless networks, a Public KeyInfrastructure (PKI) technology has been widely used. With the PKItechnology, a transmitter is able to encode transmitting informationusing a receiver's private key which is retrieved from the electroniccertificate of the receiver. Then, the receiver who receives thatinformation can read the information by decoding the receivedinformation using the private key, which is not known to others.

In order to maintain a security system based on the PKI, it has to beconfirmed whether the public key, which is open to the public, in factbelongs to the user who is asserting ownership of that key. Such a taskcan be confirmed through a digital certificate which is issued by acredible third party, i.e., a Certificate Authority (CA) by means ofattaching its digital signature to the public key of the owner.

However, the PKI system requires a lot of time and expense to create andmanage the public and private keys and issue the digital certificate bythe CA. Meanwhile, the user has to save and maintain the informationregarding the private and public keys in a disc or memory of the user'sterminal. In addition, many users save and maintain the information ofothers' digital certificates, which consumes huge expenses and is notsuitable for video communication. Therefore, there has been a need todevelop an encrypting and certifying method suitable for the videocommunication.

SUMMARY

Exemplary embodiments have been made to solve the above-mentionedproblems occurring in the prior art, and provide a method and anapparatus for performing video communication capable of processing auser certification by creating a digital key including biologicalinformation of a user.

In accordance with an exemplary embodiment, there is provided a methodfor performing video communication using terminals to assist the videocommunication, including: creating and saving a bio key using a user'sbiological information before first and second terminals perform thevideo communication; establishing a session, wherein the first terminalrequests voice communication from the second terminal; exchanging thebio keys saved in the respective terminals and saving the same; startinga Secure Real-Time Transport Protocol (SRTP) session, wherein the firstand second terminals create a session sharing key using the exchangedbio keys; creating a restored bio key by obtaining the biologicalinformation from data received by first and second terminals andperforming a user certification by comparing the bio key with therestored bio key.

The operation of creating the bio key may include the operation ofencoding and decoding the biological information; and creating a digitalbio key by extracting featuring information of the biologicalinformation.

The operation of creating the bio key may include creating a pluralityof bio keys respectively corresponding to a plurality of encoding anddecoding methods.

The method may further include the operation of selecting one of theencoding and decoding methods to be employed in the communicationamongst a plurality of encoding and decoding methods.

The session sharing key may be created on the basis of a Diffie-Hellmanalgorithm.

The biological information may include face featuring informationextracted from a featuring point of the user's face.

In accordance with another exemplary embodiment, there is provided anapparatus for performing video communication, including: an outer inputdevice that receives voice and video signals; an outer output devicethat outputs the voice and video signals; an encoding and decodingmodule that encodes and decodes the voice and video signals transferredfrom the outer input device and decodes the voice and video signalsreceived through the communication; a biological information extractingpart that obtains biological information from the video signal outputtedthrough the encoding and decoding module; a bio key creating part thatcreates and manages a bio key using the biological information outputtedfrom the biological information extracting part; a session sharing keycreating part that manages the creation of a session sharing key usingthe bio key being created and the bio key received from a terminal ofthe other party in communication; an encryption certifying part thatmanages the creation of a restored bio key and certifies the encodingoperation; and a telecommunication module transmits and receives packetdata being encoded using the session sharing key.

The encoding and decoding module may encode the video signal inputted tocreate the bio key, and then output the video signal after decoding thesame.

The encoding and decoding module may include an encoder and a decoderwhich perform various encoding and decoding operations, and the bio keycreating part may create a plurality of bio keys respectivelycorresponding to the biological information which are outputted afterbeing encoded and decoded in various ways.

The biological information extracting part may include a facial arearecognizing part that scans a facial area included in a video; and afeaturing point extracting part that recognizes the featuring point ofthe face using the geometrical information of the scanned facial area,and extracts the face featuring information with respect to therecognized featuring point of the face.

The encryption certifying part may control the biological informationextracting part that extracts the biological information from the datareceived from the terminal of the other party, and certify an encryptionby confirming whether the bio key is the same as the restored bio key.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects will be more apparent from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a block diagram illustrating a video communication apparatusin accordance with an exemplary embodiment;

FIG. 2 is a block diagram illustrating a biological informationextracting part provided in the video communication apparatus inaccordance with an exemplary embodiment;

FIG. 3A illustrates a face area perceived by the video communicationapparatus in accordance with an exemplary embodiment;

FIG. 3B illustrates a featuring point of the face area extracted by thevideo communication apparatus in accordance with an exemplaryembodiment;

FIG. 4 is a flow chart illustrating a bio key establishing process of avideo communication method in accordance with an exemplary embodiment;and

FIG. 5 is a flow chart illustrating a video communication process of thevideo communication method in accordance with an exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments will be described with reference tothe accompanying drawings. In the following description, the sameelements will be designated by the same reference numerals although theyare shown in different drawings. Further, various specific definitionsfound in the following description, such as specific values of packetidentifications, contents of displayed information, etc., are given onlyto provide a general understanding, and it is apparent to those skilledin the art that the exemplary embodiments can be implemented withoutsuch definitions. Further, in the following description of the exemplaryembodiments, a detailed description of known functions andconfigurations incorporated herein will be omitted when it may make theexemplary embodiments rather unclear. Expressions such as “at least oneof,” when preceding a list of elements modifies the entire list ofelements and does not modify each element of the list.

FIG. 1 is a block diagram illustrating a construction of a videocommunication apparatus in accordance with an exemplary embodiment.

Referring to FIG. 1, a video communication apparatus includes an outerinput device 110, an outer output device 120, an encoding and decodingmodule 210, a biological information extracting part 220, a bio keycreating part 230, a memory 240, a session sharing key creating part250, an encryption certifying part 260, and a telecommunication module270.

The outer input device 110 refers to a device in which a user inputsvoice and video signals for a video communication, including amicrophone and a camera. The outer output device 120 is designed tooutput the voice and video signals to the user which are transmittedfrom another party during the video communication, which includes aspeaker and a display device.

The encoding and decoding module 210 encodes the voice and video signalstransferred from the outer input device 110 on the basis of apredetermined encoding method, such as G 711, G 729, MPEG 4, H 264 orthe like, and then decodes the voice and video signals transmittedthrough the telecommunication module 270.

Further, the encoding and decoding module 210 includes a plurality ofencoding parts 212, 214, and 216, and a plurality of decoding parts 213,215, and 217, which perform the encoding and decoding operations,respectively corresponding to a variety of encoding and decoding methodswhich are employed by the video communication apparatus. The encodingand decoding module 210 also includes an encoding and decoding controlpart 211 which is designed to control the operations of a plurality ofencoding and decoding parts 212 to 217.

In the initial operation of a communication, the video communicationapparatus is adapted to decide the encoding and decoding method to beused in the communication. In this regard, the encoding and decodingcontrol part 211 selects an encoding part, when it begins communicating,to perform the encoding operation of the voice or video signal generatedfrom the outer input device 110 on the basis of the determined encodingmethod, and then selects a decoding part to perform the decodingoperation on the basis of the determined encoding method.

Furthermore, various encoding and decoding methods can be employed whichare assisted by the video communication apparatus of the other partywhich has performed the communication. The video communication apparatusin accordance with an exemplary embodiment encodes and decodesbiological information extracted from the voice or video signal, andthen creates a bio key on the basis of the resulting value. Since itcannot recognize in advance which encoding and decoding method has beenemployed by the video communication apparatus of the other party havingperformed the communication, the video communication apparatus inaccordance with an exemplary embodiment may create a plurality of biokeys each corresponding to a variety of encoding and decoding methodswhich are used by the video communication apparatus. Therefore, theencoding and decoding control part 211 controls the input of theencoding and decoding parts 212 to 217 so that a plurality of valuescorresponding to a plurality of encoding and decoding methods can beoutputted with respect to the inputted voice or video signal in order tocreate a plurality of bio keys using the inputted voice or video signal.

The biological information extracting part 220 has an input of the videosignal which is outputted from the encoding and decoding module 210 andextracts the biological information representing unique features of eachuser from the video signal.

The bio key creating part 230 creates a digital key (i.e., bio key)including the biological information extracted by the biologicalinformation extracting part 220 and saves the bio key in the memory 240.

The session sharing key creating part 250 transmits the bio key (a firstbio key), which has been created and saved in the memory 240, to thevideo communication apparatus of another party through thetelecommunication module, and creates a session sharing key by combiningthe first bio key and a bio key (a second bio key) received from thevideo communication apparatus of the other party. Further, the sessionsharing key creating part 250 saves the second bio key in the memory240. For instance, the session sharing key creating part 250 can createthe session sharing key on the basis of a Diffie-Hellman algorithm.

The encryption certifying part 260 performs the process of encryptioncertification after the session sharing key is created from the sessionsharing key creating part 250. The encryption certifying part 260extracts the biological information from the data after the receivedpacket data has been decoded, and controls the operations of theencoding and decoding module 210, the biological information extractingpart 220, and the bio key creating part 230 so as to create the bio keyusing the extracted biological information. With the control of theencryption certifying part 260, a bio key received from the packet data(referred to as “a restored bio key”) is created and saved in the memory240.

In addition, after the encryption certifying part 260 compares thesecond bio key which is received to create the session sharing key withthe restored bio key, it certifies whether an encryption process isproperly performed by confirming that the second bio key matches therestored bio key.

The telecommunication module 270 establishes a session for performingcommunication with the video communication apparatus of the other party,and then performs the video communication. Particularly, in order toestablish the session for performing the communication, thetelecommunication module 270 requests a signal from the videocommunication apparatus of the other party, and performs a negotiationon the encoding and decoding method to be used in the communication.Further, the telecommunication module 270 transmits the encoding anddecoding method established through the negotiation to the encoding anddecoding module 210, and performs the encoding and decoding operation ofthe packet data using the session sharing key created through thesession sharing key creating part 250.

The biological information extracting part 220 may extract thebiological information regarding a featuring point existing in theuser's face. FIG. 2 is a block diagram illustrating a detailedconstruction of the biological information extracting part 220 providedin the video communication apparatus in accordance with an exemplaryembodiment. Referring to FIG. 2, the biological information extractingpart 220 includes a facial area recognizing part 221 and a featuringpoint extracting part 222. The facial area recognizing part 221 scansthe facial area 115 included in the video on the basis of the color,brightness, facial pattern or the like outputted from the encoding anddecoding module 210 (refer to FIG. 3A). On the other hand, the featuringpoint extracting part 222 recognizes the featuring points 116, 117, 118,and 119, where a face, eyes, a nose, a lip or the like is located usingthe geometrical information of the scanned facial area (refer to FIG.3B), and then extracts the face featuring information such as the sizeof the featuring point, ratio, brightness, facial pattern or the likewhich have been recognized. Consequently, the biological informationextracting part 220 outputs the face featuring information as thebiological information, and the bio key creating part 230 creates adigital key using the face featuring information.

Hereinafter, the encrypting method of video communication in accordancewith an exemplary embodiment will be described by explaining theoperation of the video communication apparatus in accordance with anexemplary embodiment.

Before performing video communication, the video communication apparatuscreates a bio key and saves it in the memory 240. Whenever performingvideo communication, the video communication apparatus carries out auser certification using the bio key saved in advance. Accordingly, thevideo communication apparatus may be operated in a bio key establishingmode or a video communication performing mode. Operations of the videocommunication apparatus in accordance with the respective modes will bedescribed hereinbelow.

1. Bio Key Establishing Mode

FIG. 4 is a flow chart illustrating a bio key establishing process of avideo communication method in accordance with an exemplary embodiment.Referring to constructions of the video communication apparatus asdescribed above and FIG. 4, when the user first selects the function ofestablishing the bio key among the functions of the video communicationapparatus, a control part (not shown) requests the user of the videosignal to input a video signal through the outer output device 120(Operation 310) so that the user's biological information may beextracted. In response thereto, the user may input the video signalthrough the outer input device 110 (Operation 320).

The video signal inputted from the outer input device 110 is transferredto the encoding and decoding module 210. The encoding and decodingmodule 210 delivers the video signal to the first encoding part 212,controls the first encoding part 212 and the first decoding part 213 toencode and decode the video signal, and outputs the same.

The encoding and decoding control part 211 transmits the inputted videosignal to the second encoding part 214, controls the second encodingpart 214 and the second decoding part 215 to encode and decode the videosignal, and outputs the same.

The encoding and decoding control part 211 controls the encoding anddecoding parts 212 to 217, which are provided in the encoding anddecoding module 210, to repeatedly encode and decode the inputted videosignal.

It The plurality of encoding and decoding parts 212 to 217 may performencoding and decoding operations in different ways. Hence, the encodingand decoding module 210 may receive a single video signal, but mayoutput a plurality of video signals which have been encoded and decodedin different ways through the plurality of encoding and decoding parts212 to 217 (Operation 330).

Through the Operation 330 as described above, a plurality of videosignals, which have been encoded and decoded, are outputted from theencoding and decoding module 210 and transferred to the biologicalinformation extracting part 220.

In response thereto, the biological information extracting part 220extracts biological information representing unique features of therespective users from the voice or video signal (Operation 340). Inother words, the facial area recognizing part 221 of the biologicalinformation extracting part 220 scans the facial area 115 included inthe video on the basis of the color, brightness, facial pattern or thelike outputted from the encoding and decoding module 210 (refer to FIG.3 a). In contrast, the featuring point extracting part 222 recognizesthe featuring points 116 through 119 where a face, eyes, a nose, a lipor the like is located using the geometrical information of the scannedfacial area (refer to FIG. 3 b), and then extracts the face featuringinformation such as the size of the featuring points, ratio, brightness,facial pattern or the like which have been recognized.

The extracted biological information, for example, the face featuringinformation is inputted into the bio key creating part 230. The bio keycreating part 230 generates a bio key by applying an algorithm whichcreates a specific digital private key from the biological informationlike the face featuring information (Operation 350).

A plurality of bio keys created by using a plurality of video signalswhich have been encoded and decoded in different ways as described aboveare saved in the memory 240 (Operation 350).

2. Video Communication Performing Mode

FIG. 5 is a flow chart illustrating a video communication process of avideo communication method in accordance with an exemplary embodiment.Referring to the video communication apparatus as described above andFIG. 5, when the user first requests video communication among thefunctions of a first terminal 410, the control part (not shown) controlsthe telecommunication module 270 to transmit a call request to a secondterminal 450 (Operation 510). For instance, the telecommunication module270 of the first terminal 410 may transmit an INVITE message. Inresponse thereto, the second terminal 450, i.e., the video communicationapparatus of the other party, responds to the call (Operation 520).During Operations 510 and 520, the first and second terminals 410 and450 establish the encoding and decoding method for a voice signal usedin the communication such as G 711, G729 method or the like, as well asfor a video signal such as MPEG 4, H 264 method or the like.

When a media session begins after the performance of signaling asdescribed above, the session sharing key creating part 250 provided inthe first and second terminals 410 and 450 exchange bio keys which havebeen saved in each device (Operations 531 and 535). The bio keys may becreated on the basis of the Diffie-Hellman algorithm, but are notlimited to this algorithm.

In the bio key establishing mode as described above, the bio keycreating part 230 of the first and second terminals 410 and 450 createsa first bio key (BKa) and a second bio key (BKb), respectively. Incontrast, the session sharing key creating part 250 of the first andsecond terminals 410 and 450 changes the bio keys (BKa, BKb) into firstand second converted bio keys (Ya, Yb) for creating the session sharingkey, and then exchanges the converted bio keys (Ya, Yb). The firstterminal 410 stores the second converted bio key (Yb) (Operation 541)and the second terminal 450 stores the first converted bio key (Ya)(Operation 545). The first and second converted bio keys (Ya, Yb) can becreated through the following Equation 1.

Ya=pBKa·mod q; Yb=pBKb·mod q  (Equation 1)

wherein p and q are predetermined constants.

Next, the session sharing key creating part 250 of the first terminal410 creates a session sharing key by combining the first converted biokey (Ya), which has been changed and saved beforehand in the memory 240of the first terminal 410, and the second converted bio key (Yb), whichhas been newly received and saved (Operation 551). For instance, thesession sharing key creating part 250 of the first terminal 410 maycreate a session sharing key (K) through the following Equation 2.

K=YbBKa·mod q=(pBKb)BKa·mod q  (Equation 2)

Similarly, the session sharing key creating part 250 of the secondterminal 450 saves the first converted bio key (Ya) in Operation 545 andcreates the session sharing key using the first and second converted biokeys (Ya, Yb) (Operation 555). The session sharing key creating part 250of the second terminal 450 may create a session sharing key (K) throughthe following Equation 3. Consequently, the session sharing key creatingpart 250 of the first and second terminals 410 and 450 creates the samesession keys, respectively.

K=YaBKb·mod q=(pBKa)BKb·mod q  (Equation 3)

After the creation of the session keys is completed, the first terminal410 begins an SRTP session. That is, when the voice and video data areinputted from the outer input device 110 provided in the first terminal410 and then transferred to the encoding and decoding module 210, theencoding and decoding control part 211 selects one of the encodingparts, for example the first encoding part 212, which corresponds to theencoding method selected during the call establishing process. Thus, thevoice and video data delivered from the outer input device 110 areencoded through the first encoding part 212 and transferred to thetelecommunication module 270. Accordingly, the telecommunication module270 makes a packet of the voice and video data which have been encoded(Operation 560).

Then, the telecommunication module 270 encodes the data which have beenmade as a packet (referred to as “packet data”) using the sessionsharing key (Operation 570), and then transmits the encoded packet datato the second terminal 450 (Operation 580).

The second terminal 450 receives the encoded packet data through itstelecommunication module 270, and then restores the packet data usingthe session sharing key (Operation 590).

The restored data are transferred to the encoding and decoding module210, and the encoding and decoding control part 211 selects one of thedecoding parts, for example, the first decoding part 213 whichcorresponds to the encoding method selected during the call establishingprocess. Thus, the encoded voice and video data inputted from thetelecommunication module 270 are decoded through the first decoding part213 (Operation 600).

The decoded voice and video data go through the encryption certificationprocess before they are transferred to the outer output device 120. Inother words, the biological information extracting part 220 extracts thebiological information, for example the face featuring information fromthe voice and video data decoded through the same method as described inthe ‘bio key establishing mode.’ Then, the bio key creating part 230creates a restored bio key (BKa′) using the extracted biologicalinformation, for example, the face featuring information and saves themin the memory 240 (Operation 610).

Next, the encryption certifying part 260 compares the restored bio key(BKa′) with the first bio key (BKa) which is received during the processof creating the session sharing key, and confirms their coincidences(Operation 620). Furthermore, the encryption certifying part 260confirms that the encryption certification is successfully performedonly if the restored bio key (BKa′) is the same as the first bio key(BKa) received.

Finally, if the encryption certification is successfully performed, thedecoded voice and video data are transferred to the outer output device120 and outputted thereafter (Operation 630).

According to the exemplary embodiments, the encryption of the media datacan be easily performed in the terminal regardless of the constructionof the public key based structure. Further, since the key exchange andcertification are performed in the media session, it may be applicableto various signaling protocols. The security of the communication can bemaintained because the digital key is created using the user'sbiological information.

A method according to an exemplary embodiment can be embodied as acomputer readable code in computer readable recording media. Thecomputer readable recording media includes all kinds of recordingdevices in which data readable by the computer system may be saved.Examples of the computer readable recording media include ROM, RAM,CD-ROM, a magnetic tape, a floppy disc, an optical disc or the like. Thecomputer readable recording media may be distributed in a computersystem connected to networks, and may be saved and executed as acomputer readable code in a distributed method.

While certain exemplary embodiments have been shown and described, itwill be understood by those skilled in the art that various changes inform and details may be made therein without departing from the spiritand scope of the appended claims.

1. A method for performing communication the method comprising: creatinga first bio key using a first user's biological information and savingthe first bio key in a first terminal; creating a second bio key using asecond user's biological information and saving the second bio key in asecond terminal; establishing a session, wherein the first terminaltransmits a request for communication to the second terminal;transmitting the first bio key from the first terminal to the secondterminal and transmitting the second bio key from the second terminal tothe first terminal; creating a session sharing key using the first biokey and the second bio key; creating a restored bio key using at leastone of the first user's biological information and the second user'sbiological information; and performing user certification by comparingthe first bio key with the restored bio key.
 2. The method as recited inclaim 1, wherein the creating the first bio key comprises: encoding anddecoding the biological information; and creating a digital bio key byextracting featuring information of the biological information.
 3. Themethod as recited in claim 1, wherein the creating the first bio keycomprises creating a plurality of bio keys respectively corresponding toa plurality of encoding and decoding methods.
 4. The method as recitedin claim 3, further comprising selecting at least one encoding methodand at least one decoding method from the plurality of encoding anddecoding methods.
 5. The method as recited in claim 1, wherein thesession sharing key is created based on a Diffie-Hellman algorithm. 6.The method as recited in claim 1, wherein at least one of the firstuser's biological information and the second user's biologicalinformation includes face featuring information extracted from afeaturing point of the first user's face or the second user's face. 7.An apparatus for performing communication, comprising: an outer inputdevice that receives voice and video signals; an outer output devicethat outputs the voice and video signals; an encoding and decodingmodule that encodes and decodes the voice and video signals transferredfrom the outer input device and outputs a decoded video signal; abiological information extracting part that obtains biologicalinformation from the video signal outputted from the encoding anddecoding module and outputs the biological information; a bio keycreating part that creates and manages a first bio key using thebiological information outputted from the biological informationextracting part; a session sharing key creating part creates a sessionsharing key using the first bio key and a second bio key; atelecommunication module that transmits and receives packet data encodedusing the session sharing key; and an encryption certifying part thatcreates a restored bio key and certifies the packet data encoded usingthe session sharing key.
 8. The apparatus as recited in claim 7, whereinthe biological information extracting part extracts featuringinformation from the biological information; and the bio key creatingpart creates a digital bio key based on the extracted featuringinformation.
 9. The apparatus as recited in claim 8, wherein theencoding and decoding module includes a plurality of encoders and aplurality of decoders which respectively encode and decode the voice andvideo signals transferred from the outer input device according to aplurality of encoding and decoding methods, and wherein the bio keycreating part creates a plurality of bio keys respectively correspondingto the plurality of encoding and decoding methods.
 10. The apparatus asrecited in claim 7, wherein the biological information extracting partincludes: a facial area recognizing part that scans a facial areaincluded in the decoded video signal output from the encoding anddecoding module; and a featuring point extracting part that recognizes afeaturing point of the facial area using geometrical information of thescanned facial area, and extracts face featuring information withrespect to the recognized featuring point of the facial area.
 11. Theapparatus as recited in claim 7, wherein the encryption certifying partcontrols the biological information extracting part to extract thebiological information, and certifies the packet data encoded using thesession sharing key by confirming whether the first bio key is the sameas the restored bio key.
 12. A method for performing communication, themethod comprising: creating a first bio key using a user's biologicalinformation and saving the first bio key in a first terminal;transmitting, by the first terminal, a request for communication to asecond terminal; receiving a second bio key from the second terminal andstoring the second bio key; creating a session sharing key using thefirst bio key and the second bio key; encoding data using the sessionsharing key; and transmitting the encoded data to the second terminal.13. A method for performing communication, the method comprising:creating a second bio key using a user's biological information andsaving the first bio key in a second terminal; receiving a request forcommunication; receiving a first bio key from a first terminal andstoring the first bio key; transmitting the second bio key to the firstterminal; creating a session key using the first bio key and the secondbio key; creating a restored bio key using the biological information;and performing user certification by comparing the first bio key withthe restored bio key.
 14. A communication system comprising: a firstterminal and a second terminal; wherein the first terminal creates afirst bio key using a first user's biological information and saves thefirst bio key, and the second terminal creates a second bio key using asecond user's biological information and saves the second bio key;wherein the first terminal transmits a request for communication and thefirst bio key to the second terminal; wherein the second terminaltransmits the second bio key to the first terminal; wherein the firstand second terminals create a session key using the first bio key andthe second bio key; wherein the second terminal creates a restored biokey using at least one of the first user's biological information andthe second user's biological information; and wherein the secondterminal performs user certification by comparing the first bio key withthe restored bio key.